The clear evidence, the charities say, backed by thousands of individuals and organisations, is that the details of how the reform would affect disabled people has not been fully investigated.

Last week the 'Responsible Reform' report (known as the Spartacus report) revealed strong opposition from disabled people, charities and other interested groups to the Coalition Government's proposed changes to Disability Living Allowance (DLA).

The report also revealed worrying evidence that the Government’s decision to reduce DLA expenditure by 20 per cent may have been based on incomplete or misleading data about the reasons for growth in DLA.

Independent surveys have shown that cuts to DLA will force more disabled people into poverty, which is likely to increase the burden on the NHS and social care system in the long run.

"Such a potentially risky change in policy should not be taken forward without a robust and accurate evidence base and the support of disabled people and the experts in this field," say the charities in an open letter published in the Guardian newspaper.

Last year, they point out, "the Government took the bold decision to pause and reflect on its reorganisation of the NHS after similar levels of concern and anxiety from medical groups and patients. Today we are asking the Government to show similar foresight and pause the Welfare Reform Bill to investigate the strong concerns raised above."

"This call for a reflective pause in welfare reform legislation, to ensure that it is safe, reliable and fair, is a reasonable and necessary request irrespective of the outcome of votes in the House of Lords on 17 January," commented Simon Barrow, co-director of the beliefs and values thinktank Ekklesia, which has been backing the Spartacus initiative.

Yesterday Lord Freud, who is spearheading the government's attempt to force the Welfare Reform Bill through the House of Lords unreformed, dismissed the carefully researched 'Responible Reform' report as "grossly misleading". But disability campaigners say he is wrong in both fact and ethos, and have issued a reply to his points ahead of today's vital debate.

Last week the government lost three crucial amendments to the WRB in the Lords, thanks to the work of Lord Patel and other Crossbench (independent) peers, with support from Labour and a few Liberal Democrats.

The government has made some concessions, but is expected to work hard to assert its natural large majority in the second chamber today. Nevertheless it is under huge political pressure to think again, and disabled activists, charities, welfare groups, public figures and parliamentarians have pledged to continue the struggle to ensure justice for sick disabled and vulnerable people in Britain.

The full letter from charities and NGOs, published in the Guardian newspaper, reads as follows:

We are calling on the government to pause the welfare reform bill and carefully consider its reform of the DLA. The bill is now in the final stages, but the details of how the reform would affect disabled people has not been fully investigated. Last week the Responsible Reform report showed worrying evidence that the decision to reduce DLA expenditure by 20 per cent may have been based on incomplete or misleading data about the reasons for growth in DLA. It has now been revealed that the proposed changes will lead to 500,000 disabled people no longer being eligible for this benefit.

Independent surveys carried out by some of the signatories to this letter have shown that cuts to DLA will force more disabled people into poverty, which is likely to increase the burden on the NHS and social care system in the long run. Such a potentially risky change in policy should not be taken forward without a robust and accurate evidence base, and the support of disabled people and the experts in this field.

Although the views expressed in this article do not necessarily represent the views of Ekklesia, the article may reflect Ekklesia's values. If you use Ekklesia's news briefings please consider making a donation to sponsor Ekklesia's work here.